Apparatus and method for model reconstruction using photogrammetry

ABSTRACT

Disclosed herein are a model reconstruction apparatus and method using photogrammetry. The model reconstruction apparatus using photogrammetry includes an image-receiving unit for receiving image data in which images of a nail of a target, for which an artificial nail model is to be generated, and a standard specification object are taken together, an image-analyzing unit for recognizing shapes of a nail plate and a nail tip of the nail of the target from the image data, and determining parameters for the shape of the nail plate and the shape of the nail tip based on the standard specification object, and a model-generating unit for generating an artificial nail model based on the parameters.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates generally to image recognition technologyand three-dimensional (3D) modeling technology, and more particularly,to model reconstruction technology using photogrammetry.

2. Description of the Related Art

Women use artificial nails mainly of plastic materials such as a patchmade of plastic armor in order to beautify their nails. Artificial nailsthat are currently on the market are fabricated using injection moldingsuitable for standard specifications (standard sizes and curvatures). Aset of artificial nails sold to consumers may contain artificial nailscorresponding to a total of 20 to 30 pieces in such a way that there are10 to 15 sizes and two pieces are present per size. However, since thesizes, shapes, and angles of nails may differ for respective persons, itis nearly impossible for the sizes of 10 to 15 artificial nails toperfectly fit the nails of respective consumers. Due to thisdisadvantage, artificial nails are inevitably easy to distinguish fromnatural human nails, and respective users have nails of different sizes,and thus a problem may arise in that the users feel discomfort due topoor wearability, and such artificial nails are easily detached fromnatural nails.

Meanwhile, U.S. Pat. No. 6,196,234 entitled “Precision fit fingernails”and U.S. Pat. No. 6,382,217 entitled “Process for fabricating custom fitremovable and reusable metal fingernails” disclose a method forfabricating custom-fit artificial nails using molds made from a user'snails.

However, U.S. Pat. Nos. 6,196,234 and 6,382,217 are limited in that acomplicated mold-making process is required.

Further, technology entitled “Artificial Nail Manufacture ServiceSystem” in Korean Patent Application Publication No. 10-2011-0101106discloses a system for fabricating and supplying personally customizedartificial nails, which detects 3D data about the nail shape of aconsumer using a scanning system, simulates artificial nail shapes ofthe consumer meeting the consumer's request using the 3D data, and thenfabricates and provides the artificial nails.

However, technology disclosed in Korean Patent Application PublicationNo. 10-2011-0101106 is limited in user accessibility in that a 3Dscanning device dedicated to scanning nails must be used.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to conveniently and simply provide a user-customizedartificial nail model suitable for a user.

Another object of the present invention is to generate a user-customizedartificial nail model from a reference artificial nail model thatcomplies with existing standard specifications without requiring acomplicated process or special tool.

In accordance with an aspect of the present invention to accomplish theabove objects, there is provided a model reconstruction apparatus usingphotogrammetry, including an image-receiving unit for receiving imagedata in which images of a nail of a target, for which an artificial nailmodel is to be generated, and a standard specification object are takentogether; an image-analyzing unit for recognizing shapes of a nail plateand a nail tip of the nail of the target from the image data, anddetermining parameters for the shape of the nail plate and the shape ofthe nail tip based on the standard specification object; and amodel-generating unit for generating an artificial nail model based onthe parameters.

The standard specification object may be an object manufactured inconformity with international standards.

The image data may include a first image for recognizing the shape ofthe nail plate and a second image for recognizing the shape of the nailtip.

The first image and the second image may be taken in a state in whichthe standard specification object is in close contact with a bottom of afinger of the target.

The first image may be taken of the nail plate of the target togetherwith the standard specification object from a viewpoint in which a backof a hand of the target is viewed.

The second image may be taken of the nail tip together with the standardspecification object from a viewpoint in which a fingertip of the targetis viewed.

The second image may be taken in a state in which a bottom of a thumb ofthe target is in close contact with a first surface of the standardspecification object and in which all of bottoms of remaining fourfingers of the target are in close contact with a second surface of thestandard specification object.

The image-analyzing unit may recognize the shape of the nail plate fromthe first image from a viewpoint in which the back of the hand isviewed, and determines parameters for the shape of the nail plate basedon the standard specification object.

The image-analyzing unit may set at least four points on a nail wall ofthe nail plate in the first image from a viewpoint in which the back ofthe hand of the target is viewed, and may then determine the parametersusing the at least four points as coordinate values for the shape of thenail plate.

The image-analyzing unit may determine a type of a nail shape of atleast one selectable artificial nail model from the first image, basedon the shape of the nail plate recognized from a viewpoint in which theback of the hand of the target is viewed.

The image-analyzing unit may recognize the shape of the nail tip fromthe second image from a viewpoint in which the fingertip of the targetis viewed, and may determine parameters for the shape of the nail tipbased on the standard specification object.

The image-analyzing unit may set two points at positions correspondingto both sides of the nail in the second image in such a way as to setone point per position from a viewpoint in which the fingertip of thetarget is viewed, may set an additional point at at least one positionon the nail tip, and may then determine the parameters using the twopoints and the additional point as coordinate values for the shape ofthe nail tip.

The image-analyzing unit may generate a straight line connecting the twopoints, and may set a position on the nail tip, which is perpendicularto that straight line and meets a perpendicular line passing through thenail plate of the target, as the additional point.

The model-generating unit may adjust shapes of a nail plate and a nailtip of a reference artificial nail model based on the coordinate valuesfor the shape of the nail plate and the shape of the nail tip, and maygenerate the artificial nail model from the reference artificial nailmodel, the shapes of the nail plate and the nail tip of which have beenadjusted.

The model-generating unit may determine a scale value of the artificialnail model corresponding to the standard specification object based oncoordinate values of the artificial nail model and coordinate values ofthe standard specification object.

In accordance with another aspect of the present invention to accomplishthe above objects, there is provided a model reconstruction method usingphotogrammetry, performed by a model reconstruction apparatus usingphotogrammetry, including receiving image data in which images of a nailof a target, for which an artificial nail model is to be generated, anda standard specification object are taken together; recognizing shapesof a nail plate and a nail tip of the nail of the target from the imagedata, and determining parameters for the shape of the nail plate and theshape of the nail tip based on the standard specification object; andgenerating an artificial nail model based on the parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram illustrating a model reconstruction apparatususing photogrammetry according to an embodiment of the presentinvention;

FIG. 2 is a diagram illustrating an image taken of four fingers, whichare in close contact with a standard specification object, from aviewpoint in which the back of a target's hand is viewed according to anembodiment of the present invention;

FIG. 3 is a diagram illustrating an image taken of a thumb, which is inclose contact with a standard specification object, from a viewpoint inwhich the back of a target's hand is viewed according to an embodimentof the present invention;

FIG. 4 is a diagram illustrating an image taken of fingers, which are inclose contact with a standard specification object, from a viewpoint inwhich the fingertips of a target are viewed according to an embodimentof the present invention;

FIG. 5 is a diagram illustrating point settings for recognition of theshapes of nail bodies (nail plates) and determination of coordinatevalues of the nail plates in an image according to an embodiment of thepresent invention;

FIG. 6 is a diagram illustrating the types of nail shapes of selectableartificial nail models according to an embodiment of the presentinvention;

FIG. 7 is a diagram illustrating point settings for recognition of theshapes of nail tips (free edges of nails) and determination ofcoordinate values of the nail tips in an image according to anembodiment of the present invention;

FIG. 8 is a diagram illustrating detailed adjustment of an artificialnail model according to an embodiment of the present invention;

FIG. 9 is an operation flowchart illustrating a model reconstructionmethod using photogrammetry according to an embodiment of the presentinvention;

FIG. 10 is an operation flowchart illustrating in detail an example ofthe image data-receiving step of FIG. 9;

FIG. 11 is an operation flowchart illustrating in detail an example ofthe image data-analyzing step of FIG. 9;

FIG. 12 is an operation flowchart illustrating in detail an example ofthe artificial nail model-generating step of FIG. 9; and

FIG. 13 is a diagram illustrating a computer system according to anembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail below with referenceto the accompanying drawings. Repeated descriptions and descriptions ofknown functions and configurations which have been deemed to make thegist of the present invention unnecessarily obscure will be omittedbelow. The embodiments of the present invention are intended to fullydescribe the present invention to a person having ordinary knowledge inthe art to which the present invention pertains. Accordingly, theshapes, sizes, etc. of components in the drawings may be exaggerated tomake the description clearer.

In the specification, when an element is referred to as “comprising” or“including” a component, it does not preclude another component, but mayfurther include other components unless the context clearly indicatesotherwise.

Hereinafter, embodiments of the present invention will be described indetail with reference to the attached drawings.

FIG. 1 is a block diagram illustrating a model reconstruction apparatususing photogrammetry according to an embodiment of the presentinvention. FIG. 2 is a diagram illustrating an image taken of fourfingers, which are in close contact with a standard specificationobject, from a viewpoint in which the back of a target's hand is viewedaccording to an embodiment of the present invention. FIG. 3 is a diagramillustrating an image taken of a thumb, which is in close contact with astandard specification object, from a viewpoint in which the back of atarget's hand is viewed according to an embodiment of the presentinvention. FIG. 4 is a diagram illustrating an image taken of fingers,which are in close contact with a standard specification object, from aviewpoint in which the fingertips of a target are viewed according to anembodiment of the present invention. FIG. 5 is a diagram illustratingpoint settings for recognition of the shapes of nail bodies (nailplates) and determination of coordinate values of the nail plates in animage according to an embodiment of the present invention. FIG. 6 is adiagram illustrating the types of nail shapes of selectable artificialnail models according to an embodiment of the present invention. FIG. 7is a diagram illustrating point settings for recognition of the shapesof nail tips (free edges of nails) and determination of coordinatevalues of the nail tips in an image according to an embodiment of thepresent invention. FIG. 8 is a diagram illustrating detailed adjustmentof an artificial nail model according to an embodiment of the presentinvention.

Referring to FIG. 1, the model reconstruction apparatus usingphotogrammetry according to the embodiment of the present inventionincludes an image-receiving unit 110, an image-analyzing unit 120, amodel-generating unit 130, and an image-learning unit 140.

The image-receiving unit 110 may receive image data in which images ofthe nails of a target, for which a model of artificial nails is to begenerated, and a standard specification object are taken together.

First, a user terminal device may generate the image data by taking animage of the nails of the target together with the standardspecification object.

Here, the image data may be generated using various types of userterminal devices, such as a smartphone, a smart tablet, or a digitalcamera, which can take a two-dimensional (2D) digital image and thengenerate image data.

The user terminal device may request the user to generate image dataneeded to generate the model of artificial nails (hereinafter alsoreferred to as the “artificial nail model”) under the guidance of anapplication, software or a website for providing an artificial nailmodel generation service.

The application, software, or website for providing the artificial nailmodel generation service may output information needed to generate theartificial nail model as a message through the user terminal device.

The information needed to generate the artificial nail model may includea message for explaining a method for taking an image of the target'shand in order to generate the artificial nail model, and the like.

Here, the application, software, or website for providing the artificialnail model generation service may control the user terminal device sothat image data needed to generate the artificial nail model is takenusing a built-in camera installed in the user terminal device.

Also, the user terminal device may transmit the image data to the modelreconstruction apparatus using photogrammetry over a network.

Here, the user terminal device may also upload the image data onto theapplication, software, or website for providing the artificial nailmodel generation service.

The image-receiving unit 110 may receive the image data from the userterminal device over the network, or may download the image data,uploaded by the user to request the generation of artificial nails, fromthe application, software, or website for providing the artificial nailmodel generation service.

Here, the image data may include a first image for recognizing the shapeof each nail body (i.e. each nail plate) and a second image forrecognizing the shape of each nail tip (i.e. the free edge of eachnail).

It can be seen that FIGS. 2 and 3 illustrate examples of the firstimage, and that FIG. 4 illustrates an example of the second image.

Referring to FIGS. 2 to 4, the first image and the second image may betaken in the state in which a standard specification object is in closecontact with the bottoms of the fingers of the target.

In particular, as illustrated in FIGS. 2 and 3, the first image may beobtained by taking an image of the nail plates of the target togetherwith the standard specification object from a viewpoint in which theback of the target's hand is viewed.

Further, the first image may include an image taken in the state inwhich the bottom of the thumb of a left hand is in close contact withthe standard specification object from a viewpoint in which the back ofthe target's hand is viewed, an image taken in the state in which thebottoms of the remaining four fingers of the left hand are in closecontact with the standard specification object from a viewpoint in whichthe back of the target's hand is viewed, an image taken in the state inwhich the bottom of the thumb of a right hand is in close contact withthe standard specification object from a viewpoint in which the back ofthe target's hand is viewed, and an image taken in the state in whichthe bottoms of the remaining four fingers of the right hand are in closecontact with the standard specification object from a viewpoint in whichthe back of the target's hand is viewed.

In particular, as illustrated in FIG. 4, the second image may beobtained by taking an image of nail tips (free edges of nails) togetherwith the standard specification object from a viewpoint in which thefingertips of the target are viewed.

Here, the second image may include a left hand image and a right handimage taken in the state in which the bottom of the thumb of thetarget's corresponding hand is in close contact with one surface of thestandard specification object and in which all of the bottoms of theremaining four fingers are in close contact with the other surface ofthe standard specification object.

Here, in the case of the second image, the image of the fingertips ofthe target must be taken from a viewpoint opposite the direction inwhich the fingers are extended in order to recognize the extents towhich the nail tips are curved (i.e. the extents of curvature of thenail tips).

Also, the image data may further include a third image obtained bytaking an image of the sides of the fingers in order to recognize theextents to which nail plates are curved.

The standard specification object may be an object made based oninternational standards.

For example, the standard specification object may be an objectmanufactured based on international standards developed by theInternational Organization for Standardization (ISO), and the objectmanufactured based on the international standards may be any of variousobjects such as credit cards, bills, coins, and paper.

A credit card will be described below as an example of the standardspecification object according to the embodiment of the presentinvention.

The image-analyzing unit 120 may recognize the shapes of nail plates andnail tips of the nails of the target from the image data, and maydetermine parameters for the shapes of nail plates and the shapes ofnail tips based on the standard specification object.

Referring to FIG. 5, the image-analyzing unit 120 may recognize, fromthe first image, the shapes of the nail plates from a viewpoint in whichthe back of the hand is viewed, and may determine parameters for theshapes of the nail plates based on the standard specification object.

The image-analyzing unit 120 may set at least four points on the nailwall of each nail plate, from a viewpoint in which the back of thetarget's hand is viewed, in the first image, and may then determine theparameters using the at least four points as coordinate values for theshape of the corresponding nail plate.

Here, the image-analyzing unit 120 may determine the type of nail shapeof at least one selectable artificial nail model based on the shape ofthe nail plate recognized from the first image from a viewpoint in whichthe back of the target's hand is viewed.

Referring to FIG. 6, it can be seen that the types of nail shapes of theartificial nail models, which are selectable by the model reconstructionapparatus using photogrammetry according to the embodiment of thepresent invention, are depicted.

The types of nail shapes according to the embodiment of the presentinvention may include a square shape, a square oval, squoval orsemi-square shape, a rounded shape, an oval shape, an almond shape, aballerina or coffin shape, and a stiletto shape, and may further includeadditional nail shapes.

Here, the image-analyzing unit 120 may select one or more of the nailshapes of the artificial nail model in order to recommend the nail shapeof an artificial nail model to the user by comparing the recognizedshape of the nail plate of the target with the nail plate of thereference artificial nail model, and may recommend the selected nailshapes of the artificial nail model to the user through the userterminal device.

For example, when the length of the nail of a target is longer than thatof the nail of the reference artificial nail model, the image-analyzingunit 120 may select a square, square oval, squoval or semi-square shape.When the length of the nail of the target is less than that of the nailof the reference artificial nail model, the image-analyzing unit 120 mayrecommend a rounded shape. When the width of the nail of the target isless than that of the nail of the reference artificial nail model, theimage-analyzing unit 120 may select an oval or almond shape.

Also, the image-analyzing unit 120 may recognize the shape of each nailtip from the second image from a viewpoint in which the fingertips ofthe target are viewed, and may determine parameters for the shape of thenail tip based on the standard specification object.

Referring to FIG. 7, the image-analyzing unit 120 may set two points atpositions corresponding to both sides of each nail from the second imagein such a way as to set one point per position from a viewpoint in whichthe fingertips of the target are viewed, may set an additional point atat least one position on the nail tip, and may then determine theparameters using the two points and the additional point as coordinatevalues for the shape of the nail tip.

The image-analyzing unit 120 may generate a straight line connecting thetwo points, and may set a point on the nail tip, which is perpendicularto that straight line and meets a perpendicular line passing through thenail plate of the target, as the additional point.

Here, the image-analyzing unit 120 may set two points on the standardspecification object, may generate a straight line connecting the twopoints, and may adjust the locations of coordinate values for the shapeof the nail tip using the slope of the straight line generated on thestandard specification object.

Also, the image-analyzing unit 120 may recognize, from the third image,the shape of each nail side, taken from a viewpoint in which the sidesof the fingers of the target are viewed, and may determine parametersfor the shape of the nail side.

Here, the image-analyzing unit 120 may set two points at the nail tip(free edge) and the nail root of the nail plate in the third image insuch a way as to set one point at the nail tip and the other point atthe nail root from a viewpoint in which the side of each finger isviewed, may set an additional point at at least one position on the nailplate, and may then determine the parameters using the two points andthe additional point as coordinate values for the shape of the nailside.

The image-analyzing unit 120 may generate a straight line connecting thetwo points, and may set a position on the nail plate, which isperpendicular to that straight line and meets a perpendicular linepassing through the nail plate of the target, as the additional point.

Here, the image-analyzing unit 120 may set two points on the standardspecification object, may generate a straight line connecting the twopoints, and may adjust the locations of coordinate values for the shapeof the nail side using the slope of the straight line generated in thestandard specification object.

The model-generating unit 130 may generate an artificial nail modelbased on the parameters.

The model-generating unit 130 may adjust the shape of each nail platefor the reference artificial nail model based on the coordinate valuesfor the shape of each nail plate, and may generate the artificial nailmodel from the reference artificial nail model, the shape of the nailplate of which has been adjusted.

The model-generating unit 130 may adjust the shape of each nail tip ofthe reference artificial nail model based on the coordinate values forthe shape of each nail tip, and may generate the artificial nail modelfrom the reference artificial nail model, the shape of the nail tip ofwhich has been adjusted.

The model-generating unit 130 may adjust the shape of the side of eachnail plate of the reference artificial nail model based on thecoordinate values for the shape of the side of each nail plate, and maygenerate the artificial nail model from the reference artificial nailmodel, the shape of the side of the nail plate of which has beenadjusted.

The model-generating unit 130 may determine the scale value of theartificial nail model corresponding to the standard specification objectbased on the coordinate values of the artificial nail model and thecoordinate values of the standard specification object.

Also, the model-generating unit 130 may determine the scale value of theartificial nail model by comparing the coordinate values of each nailand the standard specification object, which are taken together in thefirst image, the second image, and the third image, and may thencalculate the actual size of the artificial nail model.

Here, the model-generating unit 130 may designate that the nail and thestandard specification object, taken in the first image, are located inan X-Y plane of a 3D coordinate system, may calculate the extent ofcurvature of the nail tip and the extent of curvature of the side of thenail plate based on the coordinate values recognized from the shape ofthe nail tip in the second image and the coordinate values recognizedfrom the shape of the side of the nail plate in the third image, and maycalculate a scalar space for which the extent of curvature of the nailtip and the extent of curvature of the side of the nail plate arecalculated as coordinates on a Z axis with respect to the X-Y plane,thus enabling the artificial nail model in the 3D coordinate system tobe generated.

Referring to FIG. 8, it can be seen that detailed adjustment of theartificial nail model according to an embodiment of the presentinvention is depicted.

For example, the model-generating unit 130 may finely adjust thethickness, horizontal curvature height, vertical curvature height, andnail length of the generated artificial nail model in millimeters (mm).Also, additional parameters may be further included and adjusted, andthe units of detailed adjustment are not limited thereto.

Here, the model-generating unit 130 may deliver data about the finallygenerated artificial nail model to the user through a download function(DOWNLOAD), and may store the artificial nail model through aproject-saving function (SAVE PROJECT).

In this case, the model-generating unit 130 may generate the artificialnail model in the form of a 3D model file (e.g. a stereolithography(STL) file or the like) that can be 3D-printed.

Also, the model-generating unit 130 may transfer the image data used ina procedure for generating the artificial nail model, the coordinatevalues, and the parameters adjusted from the reference artificial nailmodel to the image-learning unit 140 in order to generate learning datafrom the image data, the coordinate values, and the adjusted parameters.

The image-learning unit 140 may generate learning data by learning theimage data and the coordinate values, which are used to generate theartificial nail model, and the parameters, which are adjusted from thereference artificial nail model, and may provide the learning data tothe model-generating unit 130.

Here, the model-generating unit 130 may more effectively determine theshape and scale value of the artificial nail model in a 3D coordinatesystem using the learning data.

FIG. 9 is an operation flowchart illustrating a model reconstructionmethod using photogrammetry according to an embodiment of the presentinvention. FIG. 10 is an operation flowchart illustrating in detail anexample of the image data-receiving step of FIG. 9. FIG. 11 is anoperation flowchart illustrating in detail an example of the imagedata-analyzing step of FIG. 9. FIG. 12 is an operation flowchartillustrating in detail an example of the artificial nailmodel-generating step of FIG. 9.

Referring to FIG. 9, the model reconstruction method usingphotogrammetry according to the embodiment of the present invention mayreceive image data at step S210.

That is, at step S210, image data in which images of the nails of atarget, for which an artificial nail model is to be generated, and astandard specification object are taken together may be received.

Referring to FIG. 10, in a procedure at step S210, the image data may begenerated at step S211.

That is, at step S211, a user terminal device may generate the imagedata by taking an image of the nails of the target together with thestandard specification object.

Here, the image data may be generated using various types of userterminal devices, such as a smartphone, a smart tablet, or a digitalcamera, which can take a two-dimensional (2D) digital image and thengenerate image data.

For example, at step S211, the user terminal device may request the userto generate image data needed to generate the artificial nail modelunder the guidance of an application, software or a website forproviding an artificial nail model generation service.

At step S211, the application, software, or website for providing theartificial nail model generation service may output information neededto generate the artificial nail model as a message through the userterminal device.

The information needed to generate the artificial nail model may includea message for explaining a method for taking an image of the target'shand in order to generate the artificial nail model, and the like.

At step S211, the application, software, or website for providing theartificial nail model generation service may control the user terminaldevice so that image data needed to generate the artificial nail modelis taken using a built-in camera installed in the user terminal device.

Further, in the procedure at step S210, the image data may betransmitted at step S212.

That is, at step S212, the user terminal device may transmit the imagedata to the model reconstruction apparatus using photogrammetry over anetwork.

Here, at step S212, the user terminal device may also upload the imagedata onto the application, software, or website for providing theartificial nail model generation service.

Furthermore, in the procedure at step S210, the image data may bereceived at step S213.

That is, at step S213, the image data may be received from the userterminal device over the network, or alternatively, the image data,uploaded by the user to request the generation of artificial nails, maybe downloaded from the application, software, or website for providingthe artificial nail model generation service.

Here, the image data may include a first image for recognizing the shapeof each nail body (i.e. each nail plate) and a second image forrecognizing the shape of each nail tip (i.e. the free edge of eachnail).

It can be seen that FIGS. 2 and 3 illustrate examples of the firstimage, and that FIG. 4 illustrates an example of the second image.

Referring to FIGS. 2 to 4, the first image and the second image may betaken in the state in which a standard specification object is in closecontact with the bottoms of the fingers of the target.

In particular, as illustrated in FIGS. 2 and 3, the first image may beobtained by taking an image of the nail plates of the target togetherwith the standard specification object from a viewpoint in which theback of the target's hand is viewed.

Further, the first image may include an image taken in the state inwhich the bottom of the thumb of a left hand is in close contact withthe standard specification object from a viewpoint in which the back ofthe target's hand is viewed, an image taken in the state in which thebottoms of the remaining four fingers of the left hand are in closecontact with the standard specification object from a viewpoint in whichthe back of the target's hand is viewed, an image taken in the state inwhich the bottom of the thumb of a right hand is in close contact withthe standard specification object from a viewpoint in which the back ofthe target's hand is viewed, and an image taken in the state in whichthe bottoms of the remaining four fingers of the right hand are in closecontact with the standard specification object from a viewpoint in whichthe back of the target's hand is viewed.

In particular, as illustrated in FIG. 4, the second image may beobtained by taking an image of nail tips (free edges of nails) togetherwith the standard specification object from a viewpoint in which thefingertips of the target are viewed.

Here, the second image may include a left hand image and a right handimage taken in the state in which the bottom of the thumb of thetarget's corresponding hand is in close contact with one surface of thestandard specification object and in which all of the bottoms of theremaining four fingers are in close contact with the other surface ofthe standard specification object.

Here, in the case of the second image, the image of the fingertips ofthe target must be taken from a viewpoint opposite the direction inwhich the fingers are extended in order to recognize the extents towhich the nail tips are curved (i.e. the extents of curvature of thenail tips).

Also, the image data may further include a third image obtained bytaking an image of the sides of the fingers in order to recognize theextents to which nail plates are curved.

The standard specification object may be an object made based oninternational standards.

For example, the standard specification object may be an objectmanufactured based on international standards developed by theInternational Organization for Standardization (ISO), and the objectmanufactured based on the international standards may be any of variousobjects such as credit cards, bills, coins, and paper.

A credit card will be described below as an example of the standardspecification object according to the embodiment of the presentinvention.

Next, the model reconstruction method using photogrammetry according tothe embodiment of the present invention may analyze the image data atstep S220.

That is, at step S220, the shapes of nail plates and nail tips of thenails of the target may be recognized from the image data, andparameters for the shapes of nail plates and the shapes of nail tips maybe determined based on the standard specification object.

Referring to FIG. 5, at step S220, the shapes of the nail plates may berecognized from the first image from a viewpoint in which the back ofthe hand is viewed, and parameters for the shapes of the nail plates maybe determined based on the standard specification object.

Referring to FIG. 11, in a procedure at step S220, parameters for theshape of each nail plate may be determined first at step S221. That is,at step S221, at least four points may be set on the nail wall of eachnail plate in the first image, from a viewpoint in which the back of thetarget's hand is viewed, and then the parameters may be determined usingthe at least four points as coordinate values for the shape of thecorresponding nail plate.

Here, at step S221, the type of nail shape of at least one selectableartificial nail model may be determined based on the shape of the nailplate recognized from the first image from a viewpoint in which the backof the target's hand is viewed.

Referring to FIG. 6, it can be seen that the types of nail shapes of theartificial nail models, which are selectable by the model reconstructionapparatus using photogrammetry according to the embodiment of thepresent invention, are depicted.

The types of nail shapes according to the embodiment of the presentinvention may include a square shape, a square oval, squoval orsemi-square shape, a rounded shape, an oval shape, an almond shape, aballerina or coffin shape, and a stiletto shape, and may further includeadditional nail shapes.

Here, at step S221, one or more of the nail shapes of the artificialnail model may be selected in order to recommend the nail shape of anartificial nail model to the user by comparing the recognized shape ofthe nail plate of the target with the nail plate of the referenceartificial nail model, and the selected nail shapes of the artificialnail model may be recommended to the user through the user terminaldevice.

For example, at step S221, when the length of the nail of a target islonger than that of the nail of the reference artificial nail model, asquare, square oval, squoval or semi-square shape may be selected. Whenthe length of the nail of the target is less than that of the nail ofthe reference artificial nail model, a rounded shape may be selected.When the width of the nail of the target is less than that of the nailof the reference artificial nail model, an oval or almond shape may beselected.

Further, in the procedure at step S220, parameters for the shape of eachnail tip may be determined at step S222.

That is, at step S222, the shape of each nail tip may be recognized fromthe second image from a viewpoint in which the fingertips of the targetare viewed, and parameters for the shape of the nail tip may bedetermined based on the standard specification object.

Referring to FIG. 7, at step S222, two points may be set at positionscorresponding to both sides of each nail from the second image in such away as to set one point per position from a viewpoint in which thefingertips of the target are viewed, an additional point may be set atat least one position on the nail tip, and then the parameters may bedetermined using the two points and the additional point as coordinatevalues for the shape of the nail tip.

At step S222, a straight line connecting the two points may begenerated, and a point on the nail tip, which is perpendicular to thatstraight line and meets a perpendicular line passing through the nailplate of the target, may be set as the additional point.

Here, at step S222, two points may be set on the standard specificationobject, a straight line connecting the two points may be generated, andthe locations of coordinate values for the shape of the nail tip may beadjusted using the slope of the straight line generated on the standardspecification object.

Furthermore, in the procedure at step S220, parameters for the shape ofthe side of each nail may be determined at step S223.

The shape of each nail side, taken from a viewpoint in which the sidesof the fingers of the target are viewed, may be recognized from thethird image, and parameters for the shape of the nail side may bedetermined.

Here, at step S223, two points may be set at the nail tip (free edge)and the nail root of the nail plate in the third image in such a way asto set one point at the nail tip and the other point at the nail rootfrom a viewpoint in which the side of each finger is viewed, anadditional point may be set at at least one position on the nail plate,and then the parameters may be determined using the two points and theadditional point as coordinate values for the shape of the nail side.

At step S223, a straight line connecting the two points may begenerated, and a position on the nail plate, which is perpendicular tothat straight line and meets a perpendicular line passing through thenail plate of the target, may be set as the additional point.

At step S223, two points may be set on the standard specificationobject, a straight line connecting the two points may be generated, andthe locations of coordinate values for the shape of the nail side may beadjusted using the slope of the straight line generated in the standardspecification object.

In this case, the execution sequence of steps S221, S222, and S223included in step S220 may also be changed.

Next, the model reconstruction method using photogrammetry according tothe embodiment of the present invention may generate an artificial nailmodel at step S230.

That is, at step S230, the artificial nail model may be generated basedon the parameters.

Referring to FIG. 12, in a procedure at step S230, an artificial nailmodel may be generated by adjusting the shape of a reference nail modelat step S231.

At step S231, the shape of each nail plate for the reference artificialnail model may be adjusted based on the coordinate values for the shapeof each nail plate, and the artificial nail model may be generated fromthe reference artificial nail model, the shape of the nail plate ofwhich has been adjusted.

At step S231, the shape of each nail tip of the reference artificialnail model may be adjusted based on the coordinate values for the shapeof each nail tip, and the artificial nail model may be generated fromthe reference artificial nail model, the shape of the nail tip of whichhas been adjusted.

At step S231, the shape of the side of each nail plate of the referenceartificial nail model may be adjusted based on the coordinate values forthe shape of the side of each nail plate, and the artificial nail modelmay be generated from the reference artificial nail model, the shape ofthe side of the nail plate of which has been adjusted.

Also, in the procedure at step S230, the scale value of the artificialnail model may be determined at step S232.

That is, at step S232, the scale value of the artificial nail modelcorresponding to the standard specification object may be determinedbased on the coordinate values of the artificial nail model and thecoordinate values of the standard specification object.

Also, at step S232, the scale value of the artificial nail model may bedetermined by comparing the coordinate values of each nail and thestandard specification object, which are taken together in the firstimage, the second image, and the third image, and the actual size of theartificial nail model may then be calculated.

At step S232, the nail and the standard specification object, taken inthe first image, may be designated to be located in an X-Y plane of a 3Dcoordinate system, the extent of curvature of the nail tip and theextent of curvature of the side of the nail plate may be calculatedbased on the coordinate values recognized from the shape of the nail tipin the second image and the coordinate values recognized from the shapeof the side of the nail plate in the third image, and a scalar space forwhich the extent of curvature of the nail tip and the extent ofcurvature of the side of the nail plate are calculated as coordinates ona Z axis with respect to the X-Y plane may be calculated, thus enablingthe artificial nail model in the 3D coordinate system to be generated.

Referring to FIG. 8, it can be seen that detailed adjustment of theartificial nail model according to an embodiment of the presentinvention is depicted.

For example, at step S232, the thickness, horizontal curvature height,vertical curvature height, and nail length of the generated artificialnail model may be finely adjusted in millimeters (mm). Also, additionalparameters may be further included and adjusted, and the units ofdetailed adjustment are not limited thereto.

Here, at step S232, data about the finally generated artificial nailmodel may be delivered to the user through a download function(DOWNLOAD), and the artificial nail model may be stored through aproject-saving function (SAVE PROJECT).

In this case, the artificial nail model may be generated in the form ofa 3D model file (e.g. a stereolithography (STL) file or the like) thatcan be 3D-printed.

Also, in the procedure at step S230, learning data may be generated atstep S233.

That is, at step S233, the learning data may be generated from the imagedata and the coordinate values, which are used in a procedure forgenerating the artificial nail model, and the parameters, which areadjusted from the reference artificial nail model.

Here, at step S233, the learning data may be generated by learning theimage data and the coordinate values, which are used to generate theartificial nail model, and the parameters, which are adjusted from thereference artificial nail model.

Here, the learning data may be used at steps S231 and S232, thusenabling the shape and the scale value of the artificial nail model in a3D coordinate system to be more effectively determined.

FIG. 13 is a diagram illustrating a computer system according to anembodiment of the present invention.

Referring to FIG. 13, a model reconstruction apparatus usingphotogrammetry according to the embodiment of the present invention maybe implemented in a computer system 1100 such as a computer-readablestorage medium. Also, as illustrated in FIG. 13, the computer system1100 may include one or more processors 1110, memory 1130, a userinterface input device 1140, a user interface output device 1150, andstorage 1160, which communicate with each other through a bus 1120. Thecomputer system 1100 may further include a network interface 1170connected to a network 1180. Each of the processors 1110 may be either aCentral Processing Unit (CPU) or a semiconductor device which executesprocessing instructions stored in the memory 1130 or the storage 1160.Each of the memory 1130 and the storage 1160 may be any of various typesof volatile or nonvolatile storage media. For example, the memory mayinclude Read-Only Memory (ROM) 1131 or Random Access Memory 1132.

The present invention may conveniently and simply provide auser-customized artificial nail model suitable for a user.

Further, the present invention may generate a user-customized artificialnail model from a reference artificial nail model that complies withexisting standard specifications without requiring a complicated processor special tool.

As described above, in the model reconstruction apparatus and methodusing photogrammetry according to the present invention, theconfigurations and schemes in the above-described embodiments are notlimitedly applied, and some or all of the above embodiments can beselectively combined and configured such that various modifications arepossible.

What is claimed is:
 1. A model reconstruction apparatus using photogrammetry, comprising: an image-receiving unit for receiving image data in which images of a nail of a target, for which an artificial nail model is to be generated, and a standard specification object are taken together; an image-analyzing unit for recognizing shapes of a nail plate and a nail tip of the nail of the target from the image data, and determining parameters for the shape of the nail plate and the shape of the nail tip based on the standard specification object; and a model-generating unit for generating an artificial nail model based on the parameters.
 2. The model reconstruction apparatus of claim 1, wherein the standard specification object is an object manufactured in conformity with international standards.
 3. The model reconstruction apparatus of claim 2, wherein the image data comprises a first image for recognizing the shape of the nail plate and a second image for recognizing the shape of the nail tip.
 4. The model reconstruction apparatus of claim 3, wherein the first image and the second image are taken in a state in which the standard specification object is in close contact with a bottom of a finger of the target.
 5. The model reconstruction apparatus of claim 4, wherein the first image is taken of the nail plate of the target together with the standard specification object from a viewpoint in which a back of a hand of the target is viewed.
 6. The model reconstruction apparatus of claim 5, wherein the second image is taken of the nail tip together with the standard specification object from a viewpoint in which a fingertip of the target is viewed.
 7. The model reconstruction apparatus of claim 6, wherein the second image is taken in a state in which a bottom of a thumb of the target is in close contact with a first surface of the standard specification object and in which all of bottoms of remaining four fingers of the target are in close contact with a second surface of the standard specification object.
 8. The model reconstruction apparatus of claim 7, wherein the image-analyzing unit recognizes the shape of the nail plate from the first image from a viewpoint in which the back of the hand is viewed, and determines parameters for the shape of the nail plate based on the standard specification object.
 9. The model reconstruction apparatus of claim 8, wherein the image-analyzing unit sets at least four points on a nail wall of the nail plate in the first image from a viewpoint in which the back of the hand of the target is viewed, and then determines the parameters using the at least four points as coordinate values for the shape of the nail plate.
 10. The model reconstruction apparatus of claim 9, wherein the image-analyzing unit determines a type of a nail shape of at least one selectable artificial nail model from the first image, based on the shape of the nail plate recognized from a viewpoint in which the back of the hand of the target is viewed.
 11. The model reconstruction apparatus of claim 10, wherein the image-analyzing unit recognizes the shape of the nail tip from the second image from a viewpoint in which the fingertip of the target is viewed, and determines parameters for the shape of the nail tip based on the standard specification object.
 12. The model reconstruction apparatus of claim 11, wherein the image-analyzing unit sets two points at positions corresponding to both sides of the nail in the second image in such a way as to set one point per position from a viewpoint in which the fingertip of the target is viewed, sets an additional point at at least one position on the nail tip, and then determines the parameters using the two points and the additional point as coordinate values for the shape of the nail tip.
 13. The model reconstruction apparatus of claim 12, wherein the image-analyzing unit generates a straight line connecting the two points and sets a position on the nail tip, which is perpendicular to that straight line and meets a perpendicular line passing through the nail plate of the target, as the additional point.
 14. The model reconstruction apparatus of claim 13, wherein the model-generating unit adjusts shapes of a nail plate and a nail tip of a reference artificial nail model based on the coordinate values for the shape of the nail plate and the shape of the nail tip, and generates the artificial nail model from the reference artificial nail model, the shapes of the nail plate and the nail tip of which have been adjusted.
 15. The model reconstruction apparatus of claim 14, wherein the model-generating unit determines a scale value of the artificial nail model corresponding to the standard specification object based on coordinate values of the artificial nail model and coordinate values of the standard specification object.
 16. A model reconstruction method using photogrammetry, performed by a model reconstruction apparatus using photogrammetry, comprising: receiving image data in which images of a nail of a target, for which an artificial nail model is to be generated, and a standard specification object are taken together; recognizing shapes of a nail plate and a nail tip of the nail of the target from the image data, and determining parameters for the shape of the nail plate and the shape of the nail tip based on the standard specification object; and generating an artificial nail model based on the parameters. 